Calcite precipitation by the nitrogen-fixing cyanobacterium Anabaena sp. ATCC 33047

Area of Science:

• Geobiology
• Microbiology
• Biomineralization

Background:

• Microbiologically induced calcium carbonate precipitation (MICP) is a key ecological process.
• Cyanobacteria are known contributors to MICP, primarily through photosynthesis.
• The specific cellular mechanisms driving MICP in cyanobacteria remain unclear.

Purpose of the Study:

• To investigate the individual cell contributions to MICP in the filamentous cyanobacterium Anabaena.
• To provide direct evidence of MICP mechanisms in Anabaena under nitrogen-fixing conditions.

Main Methods:

• Quantitative microscopy was employed to observe Anabaena sp. ATCC 33047.
• Cellular interactions and crystal formation were analyzed under nitrogen-fixing conditions.

Main Results:

• MICP was observed to result from mechanical stress on vegetative cells, leading to lysis and bicarbonate release.
• A novel interaction was identified where heterocysts promote rapid calcite crystal growth upon contact with crystal seeds.
• Anabaena cells differentiate into specialized vegetative cells and heterocysts, influencing MICP.

Conclusions:

• Anabaena contributes to MICP through distinct cellular processes involving both vegetative cells and heterocysts.
• The findings reveal new insights into the interplay between cyanobacteria and calcium carbonate precipitation.
• This research enhances understanding of MICP's role in global oceanic buffering and mineral formation.